Contents

Title IDs

The organization of Title IDs has not been documented fully yet. Region info isn't stored in title IDs however there does appear to be evidence that the regions are sequential, similar to how Wii System Menu Updates are ordered: JPN USA EUR KOR and CHN (introduced with the DSi). 3DS has one additional region: TWN.

LLLLLL For CTR titles, this is the title's Unique ID. For TWL converted titles this is in two sections grouped as SSLLLL. SS is the old title identification used by the DSi and is made redundant by 'ABCD'. LLLL is the TWL title's 'Unique ID'. There are restrictions on the Unique ID, see below for more info.

RR This is the Title ID Variation, and has various uses.

Content Categories:

This u16 is a collection bit mask flag. Each Category is a group of one or more bit masks.

Specific Bitmask Flags:

Category

Bitmask

Normal

0x0

DlpChild

0x1

Demo

0x2

Contents

0x3

AddOnContents

0x4

Patch

0x6

CannotExecution

0x8

System

0x10

RequireBatchUpdate

0x20

NotRequireUserApproval

0x40

NotRequireRightForMount

0x80

CanSkipConvertJumpId

0x100

TWL

0x8000

TWL Category bit mask are carried over from original TWL category bitmasks (ignoring bit mask 0x8000), so TWL system titles have the bitmask of 0x8001.

System titles (TWL and CTR) are eligible to be updated during a System Update.

Bit Mask 0x4000 appears to be reserved, as it renders the TWL and System bit masks useless.

Unique ID Restrictions:

For the CTR titles, there appears to be is a correlation between Unique IDs (UID) and 3DS 'title types'. For developer titles this is known(shown below), and retail titles *appear* to follow suite. It is unknown if this correlation is enforced on retail units, or if it is just for organisation purposes.

TITLE TYPE

UNIQUE ID RANGE

System

0x0 - 0x2FF

Application

0x300 - 0xF7FFF

Evaluation

0xF8000 - 0xFEFFF (?)

Prototype*

0xFF000 - 0xFF3FF

Developer

0xFF400 - 0xFF7FF (?)

*On the home menu, titles with UIDs within the 'Prototype' range, appear on the home menu after install without the gift fanfare.

ProgramID/titleID low bitmask 0xF0000000(uniqueID bitmask 0xF00000) seems to be related to which hardware the title is allowed to run on. 3DS code tends to clear this bitmask when handling programIDs. This bitmask is normally zero. When this is 0x2, this indicates that the title only runs on New_3DS(that is, programID-low 0x20000000 / uniqueID 0x200000).

TitleID Variation:

This u8 allows enumeration of titles from the same category and unique ID. Common uses are explained below:

CTR System Titles: The 3DS has two copies of most modules/applets/archives for usage with either the NATIVE_FIRM or SAFE_MODE_FIRM. This is allowed for, by changing the title ID variation of the title to match the core version set by the FIRM it is designed to be used with:

RR

MEANING

02

System Title (Core version 0x2)

03

SAFE_MODE System Title (Core version 0x3)

Normally on retail SAFE_MODE ARM11 CXI titles can't be launched, since the system core version doesn't match the CXI exheader core version.

Only most non-Normal Applications are known to utilise Title ID variation, this is explained in their respective sections on this page.

Dev Menu installs CTR Applications with a TitleID variation of 0x02 to the CTR NAND.

Title ID variation is ignored for TWL titles, this value is carried over from the original TWL title ID and is used for region lock:

Versions

v## = 0xHHHH = 0bBBBBBBBB...

The version major,minor and micro can be extracted from the version number by converting the 16 bit number to binary

6 bits : Major, this matches the NCCH remaster-version.

6 bits : Minor

4 bits : Micro ('Build' in some contexts)

i.e. v2069 (Taken from 000400DB00017302) = 0b000010 000001 0101 means that the title version is v2.1.5. For reasons unknown, the CVer build, stored in the RomFS of the title, has always been zero (at time of writing), regardless of the CVer build in the TMD. So when predicting the firmware version, this should be taken into account.

Data Structure

Titles are installed to either the NAND (System and Application) or to the SD Card (Application only), and their respective directory locations are:

ID0 is the first 0x10-bytes from a SHA256 hash and ID1 is generated from the SD card CID.

Title data stored on the SD Card is encrypted with the console-unique keyslots, whereas NAND title data is stored as cleartext.

The base CTR for files stored under /title is likely based on the /title path, similar to extdata. This base CTR is unique per titleID and filename. The base CTR never changes after creation of each file.

When a newer version of a title is installed, the new .app content, .tmd, and .cmd(and .ctx for NAND titles) are written to the /title directory, however the old files here are not yet deleted. Once installation of the title is finalized, the info from import.db is moved to title.db so that the system uses the newer files instead, then the old /title files are deleted.

The title data is contained in this directory structure (note that DLC titles are stored in a different way):

"<ContentID>.tmd" - (The Content ID is a u32, initially: 00000000 when the title is first installed. Changing by an increment of +0x1 for each title update the 3DS installs) This is the Title metadata associated with the title. The decrypted TMD is available on Nintendo's CDN server at "http://nus.cdn.c.shop.nintendowifi.net/ccs/download/TitleIDhere/tmd.OptionallyTitleVersionHere". Though CDN version of the title TMD has a certificate chain attached at the end of the TMD, so removing it will give you the 1:1 decrypted TMD. After installation the "<ContentID>.tmd" is redundant, because important title data is extracted and imported into the title.db and ".cmd" files, but is however kept as a reference.

"<ContentID>.app" - (The Content ID is a u32, taken from the title's TMD) These files are NCCH files. There can be more than one NCCH in this directory, as seen with .CCI files, the game executable (CXI) can be accompanied with additional non-executable NCCH files (CFA) such as the electronic manual and DLP Child containers. Determining the function of the NCCH, is done by finding the Content Index of the "XXXXXXXX.app" file in the title's TMD(see above for retrieving decrypted TMD), interpreting the Content Index is as follows (does not apply to DLC content):

Unlike the TMD, a decrypted version of the NCCH files cannot be retrieved from Nintendo's CDN, the NCCH files do exist on Nintendo's CDN but are encrypted. Decrypting CDN versions of content, requires the title's ticket, and the common key specified by an index in the ticket. Of course editing/deleting ".app" files will have an effect. Deleting/renaming the manual ".app' will cause the manual not to load when clicked on. And deleting/renaming the executable ".app" will cause the application to not load, and the 3D Banner does not show(The banner is loaded each time from the game's executable NCCH when the home menu loads, it is not cached like the icon and name).

"<ContentID>.cmd" - (The Content ID is a u32, initially: 00000001 when the title is first installed. Changing by an increment of +0x1 for each time the 3DS adds/removes '.app' files) This file contains data taken from the title's TMD. See the below table for the format of the cleartext .cmd file. The Title.db contains the Content ID for the '.cmd' file, but does not contain a hash of the '.cmd' file. This acts as part of the DRM for installed titles, along with the title.db.

The below AES-CMACs(including the last 0x10-bytes of the header) are only used for SD titles, for NAND download-play titles, and non-system DSiWare titles. For other titles, these MACs are set to all-zero.

Offset

Size

Description

0x0

0x4

.cmd ContentID, for the .cmd filename. This is the beginning of the header.

0x4

0x4

Number of AES-CMACs and Content IDs in the first list (X). The method to determine this is explained below.

0x8

0x4

Number of Content IDs in the second list (Y)

0xC

0x4

Unknown, usually (always?) 1.

0x10

0x10

AES-CMAC over first 0x10

0x20

0x4 * X

List of installed Content IDs in order of Content Index, with missing contents replaced with 0xFFFFFFFF

0x20 + 0x4 * X

0x4 * Y

List of installed Content IDs in order of ID name

0x20 + 0x4 * (X + Y)

0x10 * X

AES-CMACs for each content in the first list, generated using the process below

The number of AES-CMACs depends on the highest Content Index installed. For example, a title with 5 contents, but only 1 and 3 are installed, will still result in 3 AES-CMACs, with the 2nd one being unused.

For SD contents, each AES-CMAC is generated by combining the NCCH header without the signature (0x100-0x1FF), the Content Index and Content ID at the end, both as u32. Then calculate the SHA256 of the data and generate the AES-CMAC using the SD/NAND AES-CMAC key.

For TWLNAND contents, the same process is used(even for SRL contents) with the keyslot for NAND dbs.

"00000001.sav" - This is the title's savegame. Renaming these savegames causes home-menu to hang while launching titles, modifying these saves results in the same corruption errors as other savegames.

"00000000.ctx" - This file is temporarily stored on SD card while a title is being downloaded from the eShop, it is deleted after the download is completed. This contains an AP0000000000000000 cert used to sign the data following the cert, this cert is signed by the CTCert.
The unknown signed data is likely an ECDSA public key. There's .ctx files stored under the /title directory for NAND CTR/TWL titles, however those use the CTXT format which is completely different from this SD .ctx format. These .ctx files for NAND/SD titles only exist for titles where installation was not yet finalized(like when a system update install was not yet finalized).

DLC Titles

DLC titles have a different directory structure to most installed titles. This is because all DLC content for a given title is installed under the same Title ID, but DLC add-ons are usually separate purchases, hence the structure altered so any combination of DLC content can be installed. DLC titles can receive 'updates', this is usually in the form of more DLC content and/or DLC bug fixes. Individual DLC content can only be managed from with-in the application using the DLC.

"00000000" - This extra directory only found in DLC titles, contains the DLC NCCH content.

"<ContentID>.tmd" - This is not modified by the 3DS, and contains the details for all DLC content(installed or not).

"<ContentID>.cmd" - This contains entries for all installed DLC NCCH content, and is updated (<ContentID> will change) every time DLC content is installed/removed.

Installing other-model system-titles

When finalizing title-install of already downloaded Old3DS system-titles to a New3DS NAND image with New3DS NATIVE_FIRM, the end result is that the New3DS version (TID-low bitmask 0x20000000) of those titles gets deleted.

It's unknown where this behaviour is implemented (might be NIM, AM, or AMXPXI).